1. Technical Field
The present invention relates to an air-sealed body and a method for manufacturing it, and more particularly to an air-sealed body with automatically opened air valves and a method for manufacturing the same.
2. Related Art
An air-sealed body is made of resin films, air columns formed by means of heat sealing into an airtight state and an air-filling port for air filling are disposed on the enclosure; the enclosure taken as a cushioning material can be used in an internal packing after air is filled in the air columns via the air-filling port.
A conventional air-sealed body disclosed in Japanese Utility Mode Laid-Open Publication No. H5-95851 entitled as “Fluid cylinder’, is configured with an independent check valve on each air column, where an air inlet at the top of each check valve is aligned with a heat-sealing line and the all check valves are coupled together; an air passage is expanded to open the check valves after air is filled in the air passage. This kind of structure, however, only allows each air column to be filled with air respectively because the check valves are independent of one another, the simultaneous filling of multiple air columns is impossible. Moreover, cylinder manufacturing is very detailed and complicated, since each check valve must be placed on a predetermined position in the cylinder one by one and heat sealing is then carried out; the check valve cannot be fixed on the cylinder, or an air inlet at the top thereof is positioned beyond the heat-sealing line sealed by a heat-sealing mold once the placement position of the check valve or the position of the sealing of the heat-sealing mold deviates from a normal position; this makes it impossible for the cylinder to be filled with air because the check valve cannot be opened following the expansion of the air passage, even if the air passage is expanded after the air passage is filled with air.
Another air-sealed body structure is disclosed in Taiwan Patent No. 00587049 entitled as “Assembly Structure of Switch Valve of Air-sealed body and Apparatus for Manufacturing Air-sealed body with Switch Valves”, wherein two sheets of inner film and one sheet of outer film at one side are adopted to adhere one another together to form a passage of a switch valve for the opening and closing of the entrance of air into the enclosure, and the enclosure is expanded to block the passage after air is filled therein. The patent only describes how to block the air in the enclosure to prevent it from leaking through the switch valve. However, the switch valve will not be pulled apart outward with the two sheets of outer film even if the two sheets of outer film are pushed by the air and then pulled apart outward when the air is guided into the passage to fill in and expand it. The two sheets of inner film will therefore still attach to each other and an air inlet cannot be opened. Obviously, air cannot enter the enclosure automatically according to the design of the patent.